AB1041 AUTOMATED VERTEBRAL FRACTURE ASSESSMENT AS A SCREENING TOOL IN PATIENTS WITH AXIAL SPONDYLOARTHRITIS
Authors: M. Siderius, L. Bares, N. Littmann, G. Richter, Y. Van der Knaap, R. Slart, A. Spoorenberg, S. Arends
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Bone loss reflected by low bone mineral density (BMD) is common in axial spondyloarthritis (axSpA) and often already noticed at early stages of disease. Severe bone loss may lead to vertebral fractures (VF). Prevalent VF, low BMD and older age are well-known risk factors for the development of new VF. Manual assessment of VF according to the method of Genant et al.1 is considered as the gold standard, however, this is time consuming in research and clinical settings. Nowadays, when performing BMD measurements an automated VF assessment (aVFA) can be generated which potentially could be a useful screening method for detecting VF in patients with axSpA. <h3>Objectives</h3> To investigate the performance of aVFA in comparison to manual assessment of radiographic VF according to Genant method in patients with axSpA. <h3>Methods</h3> In this pilot study, we included axSpA patients from the GLAS cohort who underwent DEXA with aVFA and had spinal radiographs available within 1 year. Two independent trained readers assessed the vertebral bodies on the lateral view of the thoracic and lumbar spine for radiographic VFs. Anterior, middle, and posterior heights of the 4th thoracic vertebra (Th4) to the 4th lumbar vertebra (L4) were exactly measured. VFA scans were analyzed from T4 to L4 by using a viewer (QDR, Hologic) with software supplied by the manufacturer in which a computer-aided fracture assessment semi-automatically performs total vertebral assessment for each vertebra (T4–L4) on a lateral VFA image. In both methods, radiographic VF were defined according to the method of Genant et al.<sup>[1]</sup>. A prevalent VF was defined as ≥20% reduction in any vertebral height. Vertebrae were categorized as grade 0 (normal, &lt;20% height reduction), grade 1 (mild, ≥20-&lt;25% reduction), grade 2 (moderate, ≥25-≤40% reduction) or grade 3 (severe, &gt;40% reduction) fractures. Agreement was compared at vertebral level. <h3>Results</h3> In total, 40 axSpA patients were included; 58% were male, mean age was 46.2±14.2 years, mean symptom duration was 18.0±12.4, 80% were HLA-B27 positive, mean ASDAS was 2.1±1.0 and median mSASSS (n=35) was 5.2 (IQR 1.2-18.3). At group level, median BMD T-score and BMD Z-score of the lumbar spine was -0.5 (-1.3-0.8) and -0.1 (-1.0-1.7), respectively. Osteoporosis was found in 1 (2.6%) patient and 15 (38.5%) patients had osteopenia, of these 56% were male and mean age was 46.7 ± 14.1years. In 477 (91.7%) vertebrae, there was absolute agreement on the aVFA and manual assessment (missing, normal or fracture and accompanying grade and fracture shape). In total, manual assessment detected 2 radiographic VF in 2 patients and aVFA detected 10 VF in 6 patients. The 2 fractures found with the manual method were seen in the lumbar spine, both grade 2 and wedged or biconcave shaped). The 10 aVFA fractures were found in the thoracic (n=5) and lumbar (n=5) spine; grade 1 (n=5), grade 2 (n=4) or grade 3 (n=1) and wedged (n=4) or biconcave (n=6) shaped. The fractures detected with manual assessment were both also detected with aVFA, but the fracture grading was different for one of these fractures (manual grade 2 vs. aVFA grade 3). 8 fractures detected with aVFA were not found with manual assessment. In 6 of these cases, the patient had extensive radiographic damage. X-ray quality was low in the 2 remaining cases. Regarding vertebrae defined as missing; aVFA could not assess 26 (5%) vertebrae compared to 8 (1.5%) for manual assessment. <h3>Conclusion</h3> In this pilot study using data from our observational cohort, aVFA seems a good first screening tool for the detection of radiographic VF in axSpA patients, since no fractures were missed. However, these VF should be confirmed with manual assessment especially in axSpA patients with extensive radiographic damage. A larger study population in which more VF can be identified is needed to more reliably calculate sensitivity and specificity of aVFA. <h3>Reference</h3> [1]Genant HK, Wu CY, van Kuijk C, Nevitt MC. Vertebral fracture assessment using a semiquantitative technique. J Bone Miner Res. 1993;8:1137–48. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Mark Siderius Consultant of: Novartis., Lucas Bares: None declared, Nigel Littmann: None declared, Gregor Richter: None declared, Yvonne van der Knaap: None declared, Riemer Slart: None declared, Anneke Spoorenberg Consultant of: Abbvie, Pfizer, MSD, UCB, and Novartis., Grant/research support from: Abbvie, Pfizer, UCB., Suzanne Arends: None declared.